notes > 2025-04-http-servers-in-go

HTTP servers in Go

This example is for plain HTTP. You should use HTTPS, either in Go directly or by putting the Go server behind a reverse proxy.

import (
    "fmt"
    "log"
    "net/http"
)

func handleIndex(writer http.ResponseWriter, req *http.Request) {
    // req.URL.Query()
    // req.URL.Path
    // req.Header["Hostname"]
    // req.RemoteAddr

    // writer.WriteHeader(http.StatusInternalServerError)
    // writer.Header().Set("Content-Type", "application/json")
}

handler := &http.ServeMux{}
handler.HandleFunc("/", handleIndex)
addr := fmt.Sprintf(":%d", port)
server := &http.Server{
    ReadHeaderTimeout: readHeaderTimeout,
    ReadTimeout:       readTimeout,
    WriteTimeout:      writeTimeout,
    IdleTimeout:       idleTimeout,
    Addr:              addr,
    Handler:           handler,
}
log.Fatal("server failed", server.ListenAndServe())

Use your own http.ServeMux rather than http.HandleFunc and http.ListenAndServe; libraries like net/http/pprof can add their own endpoints to the latter, which you don't want to accidentally expose to the public.
Each request is handled in its own goroutine. So you must synchronize access to shared state. Panics are caught by the framework and transformed into HTTP 500 errors.
Handlers that do long-running work should terminate when the req.Context().Done() channel is closed.
URL patterns ending with / match a prefix, not a whole path. So the URL pattern /static/ matches not just /static/ but also /static/index.js (unless already matched by a more specific pattern).

HTTP servers in Go

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